This invention relates to chemical mechanical polishing systems. Specifically this invention relates to a tool for installing a polishing pad to a polishing fixture.
Integrated circuits are often fabricated from semiconductor wafers. The surfaces of semiconductor wafers are finely polished and planarized using chemical mechanical polishing (CMP) processes. Many of these polishing processes use a polishing fixture that includes a disk-shaped polishing platen. The polishing platen of a polishing fixture is operative to accept one or more polishing pads that are adhesively bonded to the planar surfaces of the platen. When a substrate such as a semiconductor wafer is placed adjacent the polishing fixture, the polishing pad is operative to polish and planarize the surface of the wafer.
Polishing pads include an adhesive layer. The adhesive layer is comprised of a pressure sensitive adhesive (PSA) that is operative to adhere the polishing pad to the platen of the polishing fixture. Polishing pads are manufactured with a protective release liner that overlies the adhesive layer of the polishing pad. The release liner is typically comprised of a flexible plastic planar membrane which must be peeled away from the adhesive layer prior to mounting the polishing pad to a polishing fixture.
To avoid producing aberrations in the surface of a wafer and to prolong the operational lifetime of a polishing pad, the polishing pad must be installed on the platen without pockets of trapped air. In prior art installations of a polishing pad, air pockets are removed by rolling a roller over the pad. Polishing pads often include a plurality of channels in their adhesive layers which enable trapped air to escape as the roller is rolled over the pad. Unfortunately, rollers are often unable to produce a uniform bond between the entire adhesive layer of the pad and the platen. In those areas where the adhesive bond is weak, the pad may delaminate from the platen. Such pad delamination can produce waves or bubbles in the pad which may produce aberrations in the surface of a wafer. Consequently, there exists a need for a pad installation tool which is operative to uniformly bond the adhesive layer of a polishing pad to a polishing fixture.
Polishing fixtures may include slurry and blow off holes in their platens which direct slurry and gasses to the surface of a wafer being planarized and polished. The polishing pads for these types of platens include corresponding holes through the polishing pad. Such pads when installed on the platen must be properly aligned to achieve proper registration between the holes of the platen and pad. In addition the adhesive of the pad around the holes must be uniformly sealed to prevent slurry from gradually xe2x80x9cwickingxe2x80x9d between the polishing pad and platen. Slurry underneath a pad will attack the adhesive layer of the pad, resulting in bubbles and eventual delamination of the pad from the polishing fixture.
Unfortunately, the process of using a roller to install a pad on a platen with slurry and blow off holes often does not achieve a uniform adhesive bond around the holes of the platen. Consequently, there exists a need for a process of installing polishing pads which are operative to produce a uniform adhesive seal around the slurry and blow-off holes of a polishing fixture platen.
It is an object of the present invention to provide a tool for installing a polishing pad to a polishing fixture.
It is a further object of the present invention to provide a polishing pad installation tool that removes air pockets from between a polishing pad and a polishing fixture.
It is a further object of the present invention to provide a polishing pad installation tool that produces a uniform adhesive bond between a polishing pad and a polishing fixture.
It is a further object of the present invention to provide a polishing pad installation tool that produces a tight adhesive seal around slurry and blow holes of a polishing fixture platen.
Further objects of the present invention will be made apparent in the following Best Modes for Carrying Out Invention and the appended claims. Embodiments of the invention will now be described with reference to the accompanying drawings.